华北地区跨断层前兆异常特征综述

本文对《中国震例》系列书籍及期刊所记录的华北地区存在震前跨断层形变异常的震例进行了综述, 分析了华北地区不同区域跨断层前兆异常特征。 首都圈地区3次6级以上地震之前1~3年, 围绕震中会出现10~30项跨断层形变异常, 其中超过8成异常场地位于距震中100 km范围以外, 有7~8成的异常测项表现为趋势的加速或转折变化, 异常幅度集中在1~3 mm, 在异常发展过程中或者在加速达到峰值后恢复过程中发震。 随着震级的降低, 近场跨断层异常增加, 对于5~6级左右地震, 无论远场近场均会出现2~8项水准异常, 而5级以下地震前跨断层形变异常只有1~2项且主要分布在近场。

A Review of Precursory Anomalies of Cross-fault Observation in North China

We review cross-fault deformation anomaly before the earthquake cases recorded in China Earthquake Cases series and periodicals in North China. We analyze the features of these anomalies in different regions across North China. In 1~3 years prior to the three M6 or lager earthquakes, there were some 10 to 30 cross-fault deformation anomalies in the Capital region, of which more than 80% abnormal sites are located 100 km or further away from the epicenter; 70% to 80% percent of the abnormal items lasted longer than one year and notebly the accelerating or transition; anomal amplitude were concentrated in 1~3 mm; the quakes occured either in development of anomalies or the recovery period of after the abnormies number reached the peak. As the magnitude of events decreased, anomalies increased in the near-field (within 100km from epicenters). For M5 earthquakes, 2~8 items of anomalies appear in both near-field and far-field. For M4 earthquakes, there are only 1~2 items of anomalies and are mainly distributed in the near-field.